Dump delay valve

Abstract

A delay valve has a body defining an enclosure, with a separating plate and diaphragm operator therein to define an input, output and third chamber. The input and output chambers are adjacent, and separated by the separating plate. This plate defines an aperture, an umbrella valve opening and a port, all of which communicate between the input and output chambers. A stem and seal arrangement is affixed to and operable by the diaphragm operator against the bias force of a spring, to seal communication through the port at and above a pressure differential between the output and third chambers. As the input chamber vacuum decreases, the output chamber vacuum level likewise decays through the aperture at a relatively slow rate. When the pressure differential between the output and third chambers is inadequate to overcome the bias force of the spring, the port opens and thus produces equilibrium between the input and output chambers. This delay valve thus rapidly returns to an equilibrium position and is again ready to commence controlling without awaiting a slow decay return to equilibrium.

What is claimed is: 
     
       1. A dump delay valve, comprising: a wall structure defining an enclosure,   a separating plate mounted in said enclosure, defining an input chamber and an output chamber, which separating plate defines a port, an aperture and an umbrella valve opening between the input and output chambers,   an umbrella valve mounted in said input chamber on the separating plate, to cover said umbrella valve opening,   a diaphragm operator, mounted in the output chamber defining a third chamber, with the output chamber adjacent the separating plate, which diaphragm operator separates and seals the output and third chambers from each other,   a mounting plate affixed to the diaphragm operator in said output chamber,   said wall structure defining an input port for the input chamber, an output port for the output chamber, and an aperture to communicate said third chamber to atmosphere,   a stem positioned in the output chamber, which stem is affixed to said mounting plate and operable by the diaphragm operator,   a seal means affixed near one end of the stem and positioned to abut said separating plate port, and   a bias spring with a known bias force, positioned in the output chamber to bias the diaphragm operator and stem to open the separating plate port when the pressure difference between the output and third chambers is less than the bias force of the spring.   
     
     
       2. A dump delay valve as claimed in claim 1, in which the separating plate aperture is a fixed orifice. 
     
     
       3. A dump delay valve as claimed in claim 1, and further comprising a porous plug mounted in the separating plate aperture to thereby allow a restricted fluid flow between the input and output chambers. 
     
     
       4. A dump delay valve as claimed in claim 1, wherein the seal means operates in the output chamber and the umbrella valve in said input chamber opens to communicate with said output chamber. 
     
     
       5. A dump delay valve as claimed in claim 4, which valve is responsive to a decreasing vacuum input to open said separating plate port when input vacuum is less than output vacuum, and the bias spring force is greater than the pressure differential between the third chamber and the output chamber. 
     
     
       6. A dump delay valve as claimed in claim 4, which valve operates when said seal means closes communication through said separating plate port to allow a controlled rate of fluid flow and pressure increase from the input chamber to the output chamber, from a first pressure depression in said output chamber up to a smaller pressure depression in said input chamber, at which pressure depression said bias spring is operative to bias open said seal means to thereby instantaneously balance the pressure in said input and output chambers at a predetermined pressure depression below atmospheric pressure. 
     
     
       7. A dump delay valve as claimed in claim 1, wherein said seal means is operable under urging of the bias spring to instantaneously open and communicate between the input and output chambers, where said bias spring has a force greater than or equal to the difference between atmospheric pressure and the pressure level in the output chamber. 
     
     
       8. A dump delay valve as claimed in claim 1, wherein a porous plug is inserted in the separating plate port to control the rate of change of the difference between the fluid pressures in the input and output chambers. 
     
     
       9. A dump delay valve, comprising: a wall structure defining an enclosure,   a separating plate mounted in said enclosure and defining an input chamber and an output chamber, which separating plate defines a port, an aperture and an umbrella valve opening between the input and output chambers,   an umbrella valve mounted in said output chamber on the separating plate, to cover and seal said umbrella valve opening,   a diaphragm operator having two flat surfaces, mounted in the output chamber to define a third chamber, with the output chamber adjacent the separating plate, which diaphragm operator separates and seals the output and third chambers from each other,   a pair of mounting plates, one affixed to each flat surface of the diaphragm operator,   said wall structure defining an input port for the input chamber, an output port for the output chamber, and an aperture to communicate said third chamber to atmosphere,   a stem positioned in the output chamber and affixed to one of said diaphragm operator mounting plates, and extending through said separating plate port into said input chamber,   a seal means affixed at the end of said stem and positioned to abut said separating plate port,   a bias spring with a known force, positioned in the third chamber, and   said wall structure defining an end wall, between which end wall and second mounting plate of the diaphragm operator the bias spring is positioned to bias said diaphragm operator and stem to open the separating plate port when the pressure difference between the output chamber and the third chamber, operable on the diaphragm operator, is less than the bias force of said spring.   
     
     
       10. A dump delay valve as claimed in claim 9, wherein the separating plate aperture is a fixed orifice. 
     
     
       11. A dump delay valve as claimed in claim 9, and further comprising a porous plug mounted in the separating plate aperture to thereby allow a restricted fluid flow between input and output chambers. 
     
     
       12. A dump delay valve as claimed in claim 9, wherein the seal means is operative in the input chamber and the umbrella valve in said output chamber opens to communicate with said input chamber. 
     
     
       13. A dump delay valve as claimed in claim 12, which valve operates to allow a controlled rate of pressure decrease from a first elevated pressure output level above atmospheric pressure down to a second elevated pressure above atmospheric pressure in said output chamber, where said bias spring is operative to bias open said seal means to thereby instantaneously balance the pressure in said input and output chambers.